Half of ambulance staff across London have joined today's strike prompting a call to think before calling 999.

All emergency calls are being answered but patients with minor illnesses will not be sent an ambulance.

Jason Killens, deputy director of operations for London Ambulance, said: "Today’s industrial action is putting us under considerable pressure, and we urge all Londoners to use us wisely and only dial 999 for an ambulance if they think it is a genuine emergency.

"We recognise the right of staff to take part in the industrial action over the Government’s proposed pension reforms, and we’re working closely with unions to enable us to reach our most seriously ill and injured patients as quickly as possible.

"In the first few hours of action, around half of our staff were either working normally or providing emergency cover as agreed with the unions.

"We are prioritising our response so that our most seriously ill and injured patients get help quickly, but some people, who are not in a life-threatening condition, are having to wait longer than normal for an ambulance response.

"While staff will be answering all 999 calls, some patients with minor illnesses or injuries – such as back pain, upset stomachs or small cuts and bruises – will not receive an ambulance response.

"Instead, they will be given advice on how to look after themselves or told where else to seek help.

"People should only dial 999 in a genuine emergency.

"For all other healthcare needs, there are a range of services available.

"You can get help or advice from your local pharmacist or GP, visit a walk-in centre, minor injuries unit or urgent care centre or even make your own way to hospital – going in an ambulance does not mean you will be seen any quicker."

London firefighters are not joining today's strike. Members of the Fire Brigade's Union have been on a work to rule since November 25 but the industrial action does not affect emergency calls or visits.